The invention relates to an automatic telephone exchange system for exchanging and controlling telephones and data terminal equipments through a PCM telephone exchange.
Teletypewriter, CRT display, telephone facsimile and still picture transmission systems can be used as data terminal equipments to be exchanged and controlled by the automatic telephone exchange system of this invention.
For exchanging and controlling telephones and data terminal equipments by the PCM telephone exchange, telephones and the subscriber circuits of the telephone exchange, by convention, are connected by speech lines and control lines. Data terminal equipments and the other subscriber circuits of the telephone exchange are connected by data lines. The subscriber circuits for telephones in the telephone exchange transfer the speech signal through the speech lines and transfers the telephone control signals and the function signals through the control line. The subscriber circuits for data terminal equipments transfer the terminal data through the terminal data line.
With the above-mentioned prior telephone exchange system, when telephones or data terminal equipments are extended, the subscriber circuits for the exchange must correspondingly be increased. This leads to bulkiness and complexity of the system construction and increase of the system cost.